CVE-2023-6683

A flaw was found in the QEMU built-in VNC server while processing ClientCutText messages. The qemuclipboardrequest() function can be reached before vncservercuttextcaps() was called and had the chance to initialize the clipboard peer, leading to a NULL pointer dereference. This could allow a malicious authenticated VNC client to crash QEMU and trigger a denial of service.